Water-tube boiler.



A. D. PRATT.

WATER TUBE BOILER.

APPLlCATlON men JUNE 16. IQIG Patented July 30, 1918.

2 SHEETS-SHEET I A. D. PRATT.

WATER TUBE BOILER.

APPLICATION FILED JUNE I6. I9l6.

1 374,827. Patenteqiiilslys 191s.

4 2 S IL 522. F1. 25.

IN VEN TOR.

/ ATTORNEYS.

UNITED STATES PATENT OFFICE.

ARTHUR D. PRATT, OF NEW YORK, N. Y., ASSIGNOR TO THE BABCOCK & WILCOXCOM- PANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

WATER-TUBE BOILER.

Specification of Letters Patent.

Patented July 30, 1918.

To all whom it may concern:

Be it known that I, ARTHUR D. PRATT, a citizen of the United States,residing at New York city, borough of Manhattan in the county of NewYork and State of ew York, have invented certain new and usefulImprovements in Water-Tube Boilers, of

which the following is a specification.

My invention relates to water tube boilers and will be understood byreference to the accompanying drawings in which Figure 1 is a verticallongitudinal section, more or less diagrammatic; Fig. 2 an enlarged viewof a portion of Fig. 1; and Fig. an enlarged section on the plane of theline 33 of Fig. 1. Similar reference numerals indicate similar parts ofthe several views.

The present-day tendency is toward higher superhe'ats and one of theobJects of my invention is to meet this condition, in a standard, typeof boiler, by placing the superheater in a zone of hlgher gastemperature. In-the standard Babcock & W11- cox boiler the superheateris placed above the of boiler tubes where, fora given boiler, there issubstantially a constant gas temperature. According to the present design the superheater is placed below the bank of boiler tubes, and asuflicient number of water tubes are placed below the superheater inorder to minimize heat absorption in the latter through radiatlon fromthe fire and the hot furnace walls. The superheator boxes are placedoutside of the hot gas zone so that not only the boxes, but thehand-hole fittings will not be subjected to the action of the hot gases.

Referring to the drawings the numeral 1 designates a'bank of boilertubes expanded into upper and lower headers 2 and 3, and divided bybafiles 4 and 5 into three transverse passes. The upper headers areconnected by pipes 6 to steam and water drum 7. The lower headers areconnected to saiddrum by nipples 8. A wall 9 is extended from the baffle5 to the pipes 6, so

that the gases, after leaving the first pass at the steam uptake ends ofthe tube 1, will be directed downwardly and through the second pass.Below the main bank of tubes, and separated therefrom, is a row of tubes10 connected to the headers 2 and 3. Supported upon this row of tubes,and extending from the lower headers to the baflle 4, is a bafiie 11.The space between the bank of tubes 1 and the row 'of tubes 10, belowthe second and third passes, is sufiicient to permit the entrance of aman to repair the bafile 11. Access to this space may be had through thedoor 12. i

The boiler may be fired by any suitable means, a chain-grate stokerbeing indicated at 13. Above the ignition arch is a crosswall 14, and atthe rear of the primary combustion chamber 15 is a wall 16. Extendingacross the full width of the primary combustion chamber are rows oftubes 17 connected to short header sections 18 and 19, these latterbeing connected by nipples 20 and 21, respectively, to the headers 2 and3. The tubes 17 are of such length as to project beyond the walls 14 and16, sothat the header sections 18 and 19 will be outside of the hot gaszone. Above the water tubes 17, and in the space between said tubes andthe water tubes 10, is a superheater 1, which in the form shown,comprises a series of U-shaped tubes 22 connected to boxes 23 and 24,and a series of similar tubes 25 connected to boxes 26 and 27. Theplanes of the superheater tubes are inclined and their junction with theboxes are on o posite sides of the lower nipples 21, as indicated 1nFig. 3. The superheater boxes are outside of nipples 21 and of the planeof the headers 3, and thus outside of the hot gas zone, so that both theboxes and their handhole fittings 28 are not subjected to the hot gases.Steam is taken from the drum 7 through a pipe 29 to box 23, and afterflowing through the tubes 22 passes from box 24 to box 26, thencethrough the tubes 25 to the outlet box 27. The nipples 20 are spacedapart sulficiently to admit a dusting lance for the purpose of cleaningthe superheater tubes.

.The gases from the furnace flow from the primary combustion chamberacross the water tubes 17 into the secondary'combustion chamber inwhichthe su erheater is placed. The latter, therefore, a though in a lheeneral arrangement of the water tubes 1s m rec groups, the lowermostcompristhe main bank 1, and the intermediate group, the row of tubes Asdescribed,

the intermediate group is separated from both the lowermost and theuppermost I groups of tubes to provide an access space and a secondarycombustion chamber.

What I claim and desire to secure by Letters Patent of the United Statesis 1. A Water tube boiler having horizontally extending tubes connectedto upper and lower headers, said tubes being divided into separatedgroups, vertically extending nipples connecting the headers of the roupsof tubes, and a superheater having hori'- zontal headers at differentlevels in front of the lower boiler headers and U-shaped tubes extendingfrom the headers into the space it atween the groups of Water tubes,said l-shaped tubes embracing the nipples between which they extend andcausing a parallel flow of the steam through the tubes from the headerbox at one level to .the header box at another level.

2. A Water tube boiler having horizontally extending tubes connected toupper and lower headers, said tubes being divided into separated groups,nipples connecting the headers of the groups of tubes, a superheater inthe spacebetween said groups, said superheater comprising U-shaped tubesarranged With their legs extended between and beyond the front of thelower nipples, external cross boxes to Which the superheater tubes areconnected, the flow of the gases being substantially unobstructedthrough the lower water tubes and supJerheater tubes, and the uppergroup'of tu es having baffling arranged to direct the gases in back andforth passes thereover.

In testimony whereof I have hereunto signed my name in the presence oftwo subscribing Witnesses.

ARTHUR D. -lPRA'lT.

Witnesses:

R. E. BUTLER, JOHN A. W. DIXON.

